With regard to this kind of apparatus, a drive assist apparatus is known (See JP 2012-0162130). When the shift lever of a vehicle is operated to the reverse position, the drive assist apparatus displays an image in which an estimated trajectory of the vehicle is superimposed on rear video footage captured by an onboard camera. The estimated trajectory is calculated using a navigation ECU on the basis of detection results from onboard components, such as a speed sensor and steering sensor, and vehicle parameters.
When a route of the vehicle estimated in accordance with the steering angle is presented on a portable terminal apparatus which is not incorporated in an onboard apparatus, the terminal apparatus may have to successively acquire steering signals from the onboard apparatus. In this case, processing information requires a long time, which will raise a problem of delaying a timing of presenting the estimated route.